Impacts on Conventional Generators
NREL's analyses of impacts of renewable electricity generation on conventional generators show that, although the emissions impacts of generator cycling and part-loading can be significant (e.g., combined-cycle generators), these impacts are modest compared to the overall benefits of replacing fossil-fuel generation with variable renewable generation.
The Western Wind and Solar Integration Study - Phase 2 investigated the cost and emissions associated with increased cycling and ramping of conventional fossil-fueled generation due to higher levels of solar and wind generation. Key findings include that part-load emissions impacts increase the NOx benefits of wind by approximately 8%, while startups and ramping emission impacts reduce the NOx benefits of wind by approximately 4% (based on re-analysis of the Western Wind and Solar Integration Study generation profiles).
To find out more about this study, see Impacts of Wind and Solar on Fossil-Fueled Generators.
- Impacts of Renewable Generation on Fossil Fuel Unit Cycling: Costs and Emissions, Presentation (2012)
- How Does Wind Affect Coal? Cycling, Emissions, and Costs, Presentation (2011)